| As the environmental problem caused by the traditional internal combustion engine vehicle emissions is increasingly serious, the development of cleaner, more environmentally friendly new energy vehicles has become the main development trends of automobile industry in the future. The pure electric vehicle(PEV) as one of new energy vehicles has zero-emission, lower-noise, and simpler mechanical structure and other characteristics, so its prospects are bright. The vibration excitation induced by the powerplant resulting from the integration design of the drive motor, fixed ratio gear reducer and differential and the random excitation brought by the uneven rough road become the two major vibration source of pure electric cars, improving the vibration isolation characteristics of the powerplant is one of the most important processes of the vehicle’s NVH performance design, has a significant impact on ride comfort of the vehicle. A well-designed mount system can effectively reduce the vibration comes from the powerplant delivered to the car-body frame and the seat, so it is necessary to perform the vibration analysis and optimization design for an electric vehicle powerplant mount system. In this paper, I use the drive motor powerplant of a pure electric vehicle from some enterprise as the research object, based on the mechanical vibration theory and vibration isolation technology, drawing on design methods of traditional internal combustion engine mount system, accounting for the pure electric vehicle‘s unique driving features, to optimize the design of its raw mount system, and I finally find a better design solution, this process brings some practical engineering significance to certain extent. The main contents of this paper are as follows:①Formulating the dynamic model of pure electric vehicle powertrain mounting system based on Lagrange equation, and I make a modal analysis for the model by using Adams / Vibration module and MATLAB software program respectively, to recognize the mount system’s modal parameters, such as natural frequency, mode shapes and kinematic energy distribution.② Performing a qualitative analysis and research for the raw mount system excited by the drive motor output harmonic reaction torque by the method of white noise spectrum analysis(PSD) to observe the system’s steady-state response in the frequency domain, so I can access the response spectrum of dynamic reaction force at the rubber mount anchor points and powerplant centroid’s acceleration for the whole mount system.③ With the objective of maximizing energy decoupling rate, the constraints of more acceptable allocation of mount system’s natural frequency, and 18 design variables including rubber mounts’ stiffness parameters and the hardpoints’ position coordinates, the deterministic optimization model and the reliability based optimization model were established for the mount system, so a more robust and reliable mount system optimization design solution following the engineering 3σ design rule was accomplished in the Isight Parameters Optimization Frame co-simulating with MATLAB program.④ A series of transient tests were operated in accordance with the specification for pure electric vehicle powerplant mount system under 18 load cases, to obtain force and deformation data of all rubber mount, finally the displacement control method was contributed to accomplishing the elastomeric mounts’ nonlinear stiffness, and this paper fitted the corresponding nonlinear stiffness characteristics spline using MATLAB cftool Toolbox.In conclusion, the final optimized drive motor powerplant mount system represents better performance armed with more reasonable natural frequency distribution, higher energy decoupling rate and lower dynamic steady-state response amplitude of the rubber mounting supports and the powerplant centroid’s acceleration, it is proved that the optimized solution improved the vibration isolation characteristics of the mount system, being conducive to the NVH performance of the vehicle, in this paper. |
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